Hi-Speed USB Host or Device PHY With UTMI+ Interface

Datasheet

SMSC USB3450

29

Revision 0.1 (05-11-05)

DATASHEET

7.6

Suspend Detection

If a HS device detects SE0 asserted on the bus for more than 3ms (T1), it reverts to FS mode. This

enables the FS pull-up on the DP line in an attempt to assert a continuous FS J state on the bus. The

Link must then check LINESTATE for the J condition. If J is asserted at time T2, then the upstream

port is asserting a soft SE0 and the USB is in a J state indicating a suspend condition. By time T4 the

device must be fully suspended.

Figure 7.1 Reset Timing Behavior (HS Mode)

Table 7.4 Reset Timing Values (HS Mode)

TIMING

PARAMETER

DESCRIPTION

VALUE

HS Reset T0

Bus activity ceases, signaling either a reset

or a SUSPEND.

0 (reference)

T1

Earliest time at which the device may place

itself in FS mode after bus activity stops.

HS Reset T0 + 3. 0ms < T1 < HS Reset T0

+ 3.125ms

T2

Link samples LINESTATE. If LINESTATE =

SE0, then the SE0 on the bus is due to a

Reset state. The device now enters the HS

Detection Handshake protocol.

T1 + 100µs < T2 <

T1 + 875µs